Remove $cmd args/properties and deprecate mongoCmd option

Even if the "mongo.cmd" INI option is customized, the orignal "$" character may still be used. There is no functional reason to support a customizable command character in Doctrine.
Merge pull request #131
Add $rename update operator for Builder and Expr
Make full command result accessible in ArrayIterator (fixes #125)

This ensures that metadata is still accessible for command results, instead of limiting the returned value to the results array in the response document.
Merge pull request #132
Support MongoClient in Connection::isConnected()
Check for null $mongo property in Connected::getStatus()

Recent versions of the driver no longer use the $status property, so this method should likely be deprecated in the future. For the time being, at least check that the Connection's $mongo property exists (like isConnected() does) before accessing the public property.
Merge pull request #134 from doctrine/1.0.x-isConnected

Check for MongoClient and Mongo classes in Connection getters
Merge branch '1.0.x'

Conflicts:
	lib/Doctrine/MongoDB/Connection.php
added missing initialize calls to prevents usage of null objects